Anesthetic vaporizer



Oct. 15, 1963 J. A. FELTS ANESTHETIC VAPORIZER Filed Feb. 23, 1962 INVENTOR JAMES A F E L T 5 BY W ATTORNEYS United States Patent 3,186,917 A-NESTHETIC VAPORIZER James A. Felts, 517 Bainbridge Road, Marion, ill. Filed Feb. 23, 1962, Ser. No. 175,173 9 (,laims. (Cl. 123-188) This invention relates to an anesthetic vaporizer for use in closed circuit circle absorption anesthesia systems and more particularly to means responsive to a patients breathing for dispensing the liquid anesthetic in the vaporizer.

mixture through a cannister containing soda lime or some other alkaline material which will absorb acid gases. A rubber bag in the system, known as a rebreathing bag, allow-s the volume of the system to vary with the expansion and contraction of the patients lungs as he breathes.

The gaseous mixture in the anesthesia system normally circulates in only one direction. A Y connector adapts the patients face mask to the system. Check valves in the system insure that the patient exhales into one branch of the Y, through the soda lime cannister and into the rubber bag, and inhales through the other branch of the Y. The function of an anesthetic vaporizer in such a system is to receive the volatile liquid anesthetic, vaporize it and entrain it in the systems circulating gaseous mixture.

In my prior application referred to above, I disclosed and claimed an anesthetic vaporizer for closed circuit circle absorption anesthesia systems in which the liquid anesthetic was evaporated on the surface of a uniquely shaped evaporating tower enclosed in a gas tight housing. A pressure diiierential was created in a multi-chambered passageway connected in series with the circulating gaseous mixture of the closed system, and this difierential was used to divert a port-ion of the gaseous mixture through the gas tight housing where it entrained the anesthetic vapor therein. In this anesthetic vaporizer the liquid anesthetic is supplied to the top of the evaporator tower manually from a hypodermic syringe attached to a fitting in the gas tight housing. In the instant invention improved means are provided for handling and dispensing the liquid anesthetic.

Accordingly, it is a principal object of this invention to provide an anesthetic vaporizer of the kind described in which the liquid anesthetic will be administered automatically to the evaporating structure, i.e. in response to the patients breathing, thus eliminating the necessity of constant attendance and manual manipulation of a hypodermic syringe or the like by an attending anesthetist.

It is a further object of this invention to provide in an anesthetic vaporizer a reservoir for the liquid anesthetic wherein the reservoir is located within the evaporating structure.

It is a still further object of this invention to provide a compact anesthetic vaporizer which has few moving parts, thus having the attendant advantages of ease in manufacture and trouble-free performance. These and other objects and advantages of the invention will become apparent from the following specification and drawing wherein like numerals refer to similar parts throughout.

In the drawing:

FIGURE 1 is a partial section and a partial elevational view of the anesthetic vaporizer of this invention; and

FIGURE 2 is a top plan view thereof.

Briefly, the anesthetic vaporizer of this invention includes a tubular section adapted to be connected in series in the closed circuit anesthesia system. Attached to this tubular section is a gas tight housing having an evaporator tower mounted therein. Located within the evaporator tower is a liquid anesthetic reservoir, and this reservoir is in communication with the top surface of the tower permitting the liquid anesthetic to be Vaporized within the housing. A needle valve is provided to control the discharge from the reservoir. The tubular section has serially arranged areas of different pressure. A high pressure area of the tubular section is placed in communication with the reservoir to provide the pumping action, and high and low areas of the tubular section are placed in communication with a vaporization chamber within the housing for divesting a portion of the circulatin-g gas mixture to entrain the vaporized anesthetic.

Referring to the drawing which shows the preferred mode for carrying out this invention, the anesthetic vaporizer, generally designated 1%, is seen to include a niulti-charnbered tubular member 11 having a cylindrical gas tight housing 12 depending therefrom.

Mounted within the housing 12 is a vertically disposed evaporation tower 13 including an upper dome section 14 and a lower finned section 15. These sections, threadably engageable with each other at 16, are preferably fabricated from a material having high heat conduction, such as copper. The lower tower section 15 is preferably integral with a base piece 17 for better heat transmission. The base 17 is threadably engageable with the cylindrical housing 12. Formed Within the evaporation tower 13 is a liquid anestheticreservoir 18. The reservoir is adapted to be filled by a filler pipe 19 having a cap 20. Centrally located with respect to the tower 1 3 and reservoir 18 is an axially extending tube 21 which is threadably engageable at 22 with the inner surface of the dome section 14-. The tube 21 terminates a short distance above the lowermost reduced portion of the reservoir 18. It will be noted that this portion of the reservoir opens into a central aperture in the base 17 provided with a petcock 23 for draining of the reservoir. The upper end of the tube 211 is in communication with a tapered bore 24 which opens to the outside surface of the dome section 14. A needle valve 25 threaded in the top wall of the housing 12 and supported in a vertical position by a v bracket 26 extending from the tube 11 is provided to control the amount of liquid anesthetic discharging at the bore 24. A pointer 27 also attached to the tube 11 and a dial 28 having appropriate indicia thereon are provided to conveniently adjust the needle valve 25 to the desired setting.

The tubular member 11, which inter alia acts as a Venturi tube, includes the serially arranged chambers 29, 3t 31 and 32. The tubular member 11 has an inlet 33 and outlet 34 for connection into a closed circuit anesthesia system. The largest chamber 29 of the tube 11 is placed in communication with the upper portion of the reservoir 18 by means of a conduit 35. A conduit 36 places the smaller chamber 30 in communication with an evaporation chamber 37 defined by the outside of the tower 13 and the inside of the housing 12. Finally, a conduit 38 connects the chamber 32 with the evaporation chamber 37.

In operation the novel anesthetic vaporizer functions as follows: The reservoir 18 is filled with a liquid anesthetic to a level slightly below the upstanding free end of the conduit 35. This is easily accomplished by pouring the liquid into the pipe 19 until its vertical portion is completely full. The vaporizer is connected into the anesthesia system so the circulating gaseous mixture will be passing from left to right as viewed in FIGURE 1. As the patient exhales, the circulating gaseous mixture enters the inlet 33 and thereafter passes into the large chamber 29. According to Bernoullis principle, an increase in pressure will result in the chamber 29, and by means of the conduit 35 this increase in pressure will be applied to the surface of the liquid anesthetic in the reservoir 18. This action forces the liquid anesthetic into the tube 21 at the lower end thereof and out through the bore 24 onto the dome section '14 of the evaporation tower 13. The amount of liquid discharging at the bore 24 can be controlled by the needle-valve 25. The anesthetic evaporates in the chamber 37 as it passes downwardly over the tower 13 as more fully explained in my prior application, Serial No. 82,043, referred to above.

As the circulating gaseous mixture in the anesthesia system continues through the tubular member 11, it flows in chambers 30, 31 and 32 in that order. The chamber 31 tapers to a reduced opening which will increase the rate of gaseous flow as it enters the chamber 32. Again, applying Bernoullis principle a decrease in pressure will result in the chamber 32; this produces a differential in pressure with respect to the chamber 30. This pressure differential diverts a portion of the circulating gaseous mixture into the evaporation chamber 37 by means of the conduits 36, 38 for entraining the vaporized anesthetic in the gaseous mixture.

Thus it can be seen that I have provided an anesthetic vaporizer wherein a supply of liquid anesthetic is contained in a reservoir within the evaporation tower and dispensed automatically in response to the patients exhalation. The device is extremely compact and its contains few moving parts thereby insuring trouble-free operation.

While this invention has been shown in but a limited number of forms, it is obvious to those skilled in the art that it is not so limited, but it is susceptible of various changes and modifications without departing from the spirit and scope of the appended claims.

I claim:

1. An anesthetic vaporizer for use in a closed circuit anesthesia system comprising, a tubular section having a vertically disposed sealed evaporator housing attached thereto, said tubular section having serially arranged areas of different pressure including an enlarged in cross section portion to provide an area of high pressure, a decreasing in cross section portion to provide an area of high pressure, and a further decreasing in cross section portion to provide an area of low pressure, an inlet and an outlet on said tubular section for connection in said system, said housing having an evaporation tower disposed therein for vaporization of an anesthetic, a liquid anesthetic reservoir mounted within said tower and having a passageway communicating a submerged portion of the reservoir where liquid anesthetic is present with an outside upper surface of said tower, a first conduit communicating said first mentioned high pressure area of said tubular section with said reservoir at a position above surface of liquid anesthetic therewithin for forcing said anesthetic from the reservoir, second and third conduits for communicating, respectively, said next mentioned high and said low pressure areas of said tubular section with the interior of said housing, whereby a portion of a gaseous mixture circulating through said system is diverted into said housing for entraining the anesthetic vapor.

2. An anethetic vaporizer for use in a closed circuit anesthesia system comprising, a tubular section having a vertically disposed sealed vaporator housing attached thereto, said tubular section having serially arranged areas of diiferent pressure including at least one area of high pressure and a portion of reduced cross section to provide an area of low pressure, an inlet and an outlet on said tubular section for connection in said system, a finned evaporation tower disposed within said housing and defining an evaporation chamber between its outside surface and the inside surface of said housing for vaporization of an anesthetic, a liquid anesthetic reservoir mounted with in said tower and having a passageway communicating between a lower portion of said reservoir and the outside upper surface of said tower, valve means for controlling the discharge of the anesthetic from said reservoir, a first conduit communicating a high pressure area of said tubular section with the surface of said liuid anesthetic in said reservoir for forcing the anesthetic from said reservoir, second and third conduits for communicating, respectively, high and low pressure areas of said tubular section with said evaporation chamber, whereby a portion of a gaseous mixture circulating through said system is diverted into said chamber for entraining the anesthetic vapor.

3. An anesthetic vaporizer for use in a closed circuit anesthesia system comprising, a tubular section having a vertically disposed sealed evaporator housing attached thereto, said tubular section having serially arranged areas of different pressures including at least one area of high pressure and an area of reduced cross section to provide an area of low pressure, an inlet and an outlet on said tubular section for connection in said system, a vertically disposed evaporator tower disposed within said housing in spaced relation thereto, said tower including an upper dome portion and a lower finned portion defining between their outside surfaces and the inside of said housing a vaporization chamber for vaporization of an anesthetic, a liquid anesthetic reservior mounted within said tower and having a passageway communicating between a lower portion of the reservoir and the outside upper surface of said dome portion, a needle-valve at the outlet of said passageway for controlling the discharge of the anesthetic from said reservoir, a first conduit communicating a high pressure area of said tubular section with the surface of the liquid anesthetic in said reservoir for forcing the anesthetic from said reservoir, second and third conduits for communicating, respectively, high and low pressure areas of said tubular section with said evaporation chamber, whereby a portion of a gaseous mixture circulating through said system is diverted into said chamber for entraining the anesthetic vapor.

4. An anesthetic vaporizer for use in a closed circuit anesthesia system comprising, a tubular section having a vertically disposed sealed evaporator housing attached thereto, said tubular section having serially arranged areas of different pressure including at least one area of high pressure and a portion of reduced cross section to provide an area of low pressure, an inlet and an outlet on said tubular section for connection in said system, a vertically disposed evaporator tower disposed within said housing in spaced relation thereto, said tower including an upper dome portion and a lower finned portion defining between their outside surfaces and the inside of said housing a vaporization chamber for vaporization of an anesthetic, a liquid anesthetic reservoir within said tower, a passageway centrally disposed with respect to said tower and extending axially from the bottom of said reservoir to a bore opening at the surface of said upper dome portion, a needle-valve at said bore for controlling the discharge of the anesthetic from said reservoir, reservoir filling means extending from said reservoir to the exterior of said housing, a first conduit communicating a high pressure area of said tubular section with the surface of the liquid anesthetic in said reservoir for forcing the anesthetic therefrom, second and third conduits for communicating, respectviely, high and low pressure areas of said tubular section with said evaporation chamber, whereby a portion of a gaseous mixture circulating through said system is diverted into said chamber for entraining the anesthetic vapor.

5. In an anesthetic vaporizer for use in a closed circuit anesthesia system, a vertically disposed evaporator tower disposed within a sealed housing and defining an evaporation chamber between the outside surface of the tower and the inside surface of the housing for vaporization of an anesthetic, an enclosed liquid anesthetic reservoir disposed within said tower, a passageway extending upwardly from a lower portion of said reservoir to the out side surface of said tower, means for creating a greater pressure in said reservoir than in said evaporation chamber, and means for diverting a portion of a gaseous mixture circulating in said system through said evaporation chamber.

6. In an anesthetic vaporizer for use in a closed circuit anesthesia system, a vertically disposed evaporator tower disposed within a sealed housing, said tower including an upper dome portion and a lower finned portion defining between their outside surfaces and the inside of said housing a vaporization chamber for vaporization of an anesthetic, an enclosed liquid anesthetic reservoir within said tower and having a passageway having one end thereof adapted to be submerged in a liquid anesthetic therein communicating with the outside surface of said dome portion, valve means at the outlet of said passageway for controlling the discharge of the anesthetic from said reservoir, first conduit means for communicating a source of pressure with an upper portion of said reservoir for forcing the anesthetic from the reservoir, and second and third conduit means for diverting a portion of a gaseous mixture circulating in said system through said evaporation chamber.

7. In an anesthetic vaporizer for use in a closed circuit anesthesia system, a vertically disposed evaporator tower disposed within a sealed housing in spaced relation thereto, said tower including an upper dome portion and a lower finned portion defining between their outside surfaces and the inside of said housing a vaporization chamber for vaporization of an anesthetic, an enclosed liquid anesthetic reservoir within said tower, a passageway centrally disposed with respect to said tower and extending axially from the bottom of said reservoir to a bore opening at the surface of said upper dome portion, a needlevalve at said bore for controlling the discharge of the anesthetic from said reservoir, a first conduit means for communicating a source of pressure with said reservoir for forcing the anesthetic from the reservoir, and second and third conduit means for diverting a portion of a gaseous mixture circulating in said system through said evaporation chamber.

8. An anesthetic vaporizer for use in a closed circuit anesthesia system comprising, a tubular section having a vertically disposed sealed evaporator housing attached thereto, said tubular section having serially arranged areas of different pressure including at least one area of high pressure and a portion of reduced cross section to provide an area of low pressure, said tubular section having an inlet and an outlet for connection in said system, said housing having an evaporation tower disposed therein for vaporization of an anesthetic, a liquid anesthetic reservoir mounted within said tower and having a passageway extending upwardly from a lower portion of said reservoir to an outside surface of said tower, a first conduit communicating a high pressure area of said tubular section with said reservoir for forcing said anesthetic from the reservoir, second and third conduits for communicating, respectively, high and low pressure areas of said tubular section with the interior of said housing, whereby a portion of a gaseous mixture circulating through said system is diverted into said housing for entraining the anesthetic vapor.

9. In an anesthetic vaporizer, a vertically disposed evaporator tower disposed within a sealed housing and defining an evaporation chamber between the outside surface of the tower and the inside surface of the housing for vaporization of an anesthetic, an enclosed liquid anesthetic reservoir disposed within said tower, a passageway extending upwardly from a lower portion of said reservoir to the outside surface of said tower, means for creating a greater pressure in said reservoir than in said evaporation chamber means for connecting said vaporizer into an anesthetic vaporizer circuit, and means for circulating through said evaporation chamber at least a portion of gases flowing through said vaporizer; whereby the liquid anesthetic is forced through said passageway by the pressure in said enclosed reservoir.

References Cited in the file of this patent UNITED STATES PATENTS 2,141,794 King Dec. 27, 1938 2,872,167 Pratt Feb. 3, 1959 3,018,777 Dietrich Jan. 30, 1962 FOREIGN PATENTS 6,312 Great Britain May 7, 1903 718,080 Great Britain Nov. 10, 1954 

1. AN ANESTHETIC VAPORIZER FOR USE IN A CLOSED CIRCUIT ANESTHESIA SYSTEM COMPRISING, A TUBULAR SECTION HAVING A VERTICALLY DISPOSED SEALED EVAPORATOR HOUSING ATTACHED THERETO, SAID TUBULAR SECTION HAVING SERIALLY ARRANGED AREAS OF DIFFERENT PRESSURE INCLUDING AN ENLARGED IN CROSS SECTION PORTION TO PROVIDE AN AREA OF HIGH PRESSURE, A DECREASING IN CROSS SECTION PORTION TO PROVIDE AN AREA OF HIGH PRESSURE, AND A FURTHER DECREASING IN CROSS SECTION PORTION TO PROVIDE AN AREA OF LOW PRESSURE, AN INLET AND AN OUTLET ON SAID TUBULAR SECTION FOR CONNECTION IN SAID SYSTEM, SAID HOUSING HAVING AN EVAPORATION TOWER DISPOSED THEREIN FOR VAPORIZATION OF AN ANESTHETIC, A LIQUID ANESTHETIC RESERVOIR MOUNTED WITHIN SAID TOWER AND HAVING A PASSAGEWAY COMMUNICATING A SUBMERGED PORTION OF THE RESERVOIR WHERE LIQUID ANESTHETIC IS PRESENT WITH AN OUTSIDE UPPER SURFACE OF SAID TOWER, A FIRST CONDUIT COMMUNICATING SAID FIRST MENTIONED HIGH PRESSURE AREA OF SAID TUBULAR SECTION WITH SAID RESERVOIR AT A POSITION ABOVE SURFACE OF LIQUID ANESTHETIC THEREWITHIN FOR FORCING SAID ANESTHETIC FROM THE RESERVOIR, SECOND AND THIRD CONDUITS FOR COMMUNICATING, RESPECTIVELY, SAID NEXT MENTIONED HIGH AND SAID LOW PRESSURE AREAS OF SAID TUBULAR SECTION WITH THE INTERIOR OF SAID HOUSING, WHEREBY A PORTION OF A GASEOUS MIXTURE CIRCULATING THROUGH SAID SYSTEM IS DIVERTED INTO SAID HOUSING FOR ENTRAINING THE ANESTHETIC VAPOR.
 9. IN AN ANESTHETIC VAPORIZER, A VERTICALLY DISPOSED EVAPORATOR TOWER DISPOSED WITHIN A SEALED HOUSING AND DEFINING AN EVAPORATION CHAMBER BETWEEN THE OUTSIDE SURFACE OF THE TOWER AND THE INSIDE SURFACE OF THE HOUSING FOR VAPORIZATION OF AN ANESTHETIC, AN ENCLOSED LIQUID ANESTHETIC RESERVOIR DISPOSED WITHIN SAID TOWER, A PASSAGEWAY EXTENDING UPWARDLY FROM A LOWER PORTION OF SAID RESERVOIR TO THE OUTSIDE SURFACE OF SAID TOWER, MEANS FOR CREATING A GREATER PRESSURE IN SAID RESERVOIR THAN IN SAID EVAPORATION CHAMBER MEANS FOR CONNECTING SAID VAPORIZER INTO AN ANESTHETIC VAPORIZER CIRCUIT, AND MEANS FOR CIRCULATING THROUGH SAID EVAPORATION CHAMBER AT LEAST A PORTION OF GASES FLOWING THROUGH SAID VAPORIZER; WHEREBY THE LIQUID ANESTHETIC IS FORCED THROUGH SAID PASSAGEWAY BY THE PRESSURE IN SAID ENCLOSED RESERVOIR. 